1. Field of Invention
The present invention relates to a timepiece, and more particularly to a digital clock comprising a current processing circuitry which is capable of allowing an energy consumption of the digital clock of the present invention to be substantially less than that of conventional digital clocks.
2. Description of Related Arts
Conventional timepieces can broadly be divided into mechanical timepieces and digital timepieces. With the advance of electrical engineering and widespread applications of information technology, digital timepieces are becoming more popular than their mechanical counterparts. Conventional digital timepieces can in turn be broadly categorized as digital watches in which quartz crystals are used to initiate time signals (with the aid of disposable batteries as power source), and digital clocks in which Alternate Current (AC) is used as raw power source to generate electrical time signals. For the former kind of digital timepieces, an obvious disadvantage of using batteries as power source is that batteries have limited life span and users have to keep on replacing batteries periodically. For the latter kind of digital timepieces (i.e. the digital clocks), most of them require users to electrically connect the timepieces to an existing AC power socket, wherein the AC acquired from the power socket is then transformed and rectified into suitable Direct Current (DC) for use to power up the electrical components received in the digital clock.
There existing a number of different engineering designs for conventional digital clocks. Very broadly speaking, the power circuitries of conventional digital clocks are either internal or external. An internal power circuitry is permanently received in the casing, so that there is only one electric cord extending from the casing for connecting to an external AC power source. A typical internal power circuitry may comprise a transformer and a rectifying circuit received in the casing for processing AC acquired from an external AC power source for use to generate electrical time signal.
There are a number of disadvantages in association with this type of engineering design. First, the transformers used in most of the conventional digital clocks suffer from high energy loss and heat generation. This is primarily because of low frequency transformation of electrical current which leads to a relatively large amount of energy loss. In average, the transformers used in most digital clocks have a mere 30% efficiency when transforming AC. Second, most transformers used in conventional digital clocks occupy a relatively large volume of space due to the need of using a relatively large transformer core. This accordingly increases the size and weight of the corresponding casings, and explains why most digital clocks having an internal power circuitry are bulky in size. Third, many digital clocks implementing internal power circuitry design can only be used for a specified input voltage (such as 110V or 220V). In other words, users cannot use the digital clocks in different countries providing AC of different voltages. Because of the above disadvantages, conventional digital clocks consume a lot of electrical energy and most of the consumed energy is lost due to inefficient power transforming technique.
As mentioned earlier, there exist digital clocks which have external power circuitries provided out of the casing. For this kind of digital clocks, a typical user has to electrically connect a transformer hub between the digital clock and an external AC power source. While this engineering design resolves the problem of bulky casing, it merely carries the original problem to other part of the digital clock. Inefficient power transformation remains to be resolved. Moreover, since the transformer hub is now producing a substantial amount of heat and is bulky in size (because of the above mentioned reasons: namely low frequency transformation of electrical current), it poses other problems. For example, a transformer hub having high temperature may create potential risk to children.